1. Field of the Invention
The present invention relates generally to an engine muffler of heat-exchanging type. More particularly, it relates to an improved design for such an engine muffler, wherein a catalyst is used for recombustion of unburnt constituents of the engine exhaust gas for purification thereof and also an arrangement is made for efficient recovery of the thermal energy contained in said exhaust gas whose temperature is further raised by said recombustion through absorption thereof by a liquid such as water.
2. Description of the Prior Art
As an example of muffler having heat-exchanging function there has been known one with a catalyst casing surrounded by passages through which a liquid for heat-exchanging is caused to flow directly for recovery of the waste heat. In this known arrangement the recombustion system and the heat-exchanging system are formed in the same part of the muffler interior, this resulting in a complicated multi-wall structure making the muffler inevitably bulky and difficult to fabricate. Another limitation is that the catalyst is less readily accessible for replacement for the same reason.